Construction of incandescent lamps



Feb. 12, 1929. 1,701,541

F. RAY

CONSTRUCTION OF INCANDESCENT LAMPS Filed March 29, 1924 2 Sheets-Sheet i 25 E i i 12 \t 53 91 i {I 17 I i z I| 11 2'6 I} l ?0 r I ZNTOR.

Feb. 12, 1929.

1,701,541 F. RAY

CONSTRUCTION OF INCANDESCENT LAMPS Filed March 29, 1924 2 Sheets-$heet Patented Pa. 12', 1929.

UNITED STATES v PATENT OFFICE.

' rammmox rumor SHORT nnms'unw JERSEY, ASSIGNOB, BY mnsnn ASSIGNMENTS, 'ro cnaanns EISLER, or NEWARK, NEW JERSEY.

i CONSTRUCTION OF INCANDESOENT LAMPS.

Application filed mirth 29, 1924. Serial No. 702,740.

This invention relates generally to the construction of electrical incandescent lamps.

In the manufacture of electric incandescent lamps of the tipless type in which the bulbs are evacuated through the stem a common practice is to assem le into a unitary construction a filament supporting rod, a .fiare or stem tube and an exhaust member through which to exhaust the bulb. In the fusing together of these parts to form a unitary construction apassage has been provided in the wall of the flare by blowing a stream ofair into the exhaust tube so that the pressure of air at the-softened end of the tube would force its way through the mass of sof tened glass and provide the passage or port required to afford communication between the interior of the tube 'and the exterior Surface ofthe flare at. or near its junction with the filament supporting rod.

- This method of providing the perforation in the inner end of the exhaust tube has been open to the objection that the relatively cool stream of air which was blown into the exhaust tube for the purpose tended to create disadvantageous temperature [conditions within the mass of glass forming the various parts which resulted in the production of undesirable stresses and strains in the structure and contributed to the production of an unduly high percentage of breakage and waste in the manufacture of the lamps.

'It has been found that the use of the objectionable stream of air for creating the communicating perforation at the inner end of the exhaust tube can be avoided by closing the outer end of the exhaust tube before the assembling operation is eifectedand then in heating the exhaust tube to therebyheat and produce an expansion of the air trapped within the exhaust tube to bring about a de gree of pressure therein which will cause the air to force its way. through the soft and plastic wall of the flare at the junction therewith of the exhaust tube. This method of operation has thedistinct and substantial advantage that the air which is used to produce the perforation is subjected to a heating op 'eratlon such as will nullifylthe detrimental effects of the cold stream of air heretofore referred to as having been used-in the prior art. s I

In the drawings in which a preferred embodiment of the invention has-been selected M for illustration,

Figural is a view in vertical section and side elevat on of an-assemblage of lamp parts together wlth the supporting members form- 'ing part of a lamp assembling and forming machine and showing the parts in the relative positions'occup'ied while a preliminary heating step is being produced.

igure 2 is a view similar to Fi re 1 showing a clamping operation in which the fused parts are pressed together into an integral relation.

Figure 3 is a view showing the operation of producing a perforation in the wall of the structure at the inner end of the tubular exhaust tube.

Figure 4 is a view similar to Figure 3 showing a perforating operation in an assembly where the exhaust tube is joined to the flare separately from the junction of the flare with the filament supporting rod. 1 Figure 5 is a view similar to Figure 4 showing a modified form of closure for the outer end of the exhaust tube.

Referring to the drawings for a'more detailed description of the invention, Figure 1 shows a first step in the assembling of a filament supporting rod 10, a flare 11 and an exhaust tube 12 together with a pair of lead-in sageways 18 formed in the table 15. The exhaust tube 12 is supported in alinement with the filament support-ing rod 10 and is held in place between the clamping members 19 forming part of the general assembling machine.

With the parts in the relative positions indicated the nozzle 20 of a blow torch is caused to direct its flame against the lower extremity of the flare 11 to thereby soften the same as well as the adjacent extremities of the filament supporting rod 10 and the exhaust tube 12. When the flame has been applied for a sufficient length of time to bring about a desirable softening of the parts a pair of clamping j aws; 21 is brought into pinching relation tothe heated parts as in Figure 2 of the drawing and operates to press the parts into connected and unitary relation and produce a ure 5 of the drawing, the closure plug body of glass at 22 through which the lead-in.

wires 13 extend.

Followin the fusing and joining operations descri ed heat is applied to the side of the exhaust tube 12 as at 23 so that the body of air which is trapped in the exhaust tube between the closed outer end 24 thereof and the inner end which is joined to the flarepiece 11 at '25 is caused to expand whereupon the pressure of the imprisoned air breaks through the wall of the flare 11 as at 26 in Figure 3 of the drawing. The expansion of the air within the tube 12 through the application of the flame 23 theretonot only produces the desired degree of pressure within the tube but also heats the imprisoned air to a degree which prevents the setting up of undue temperature conditions within the glass with the subsequent creation of undesirable stresses and strains therein.

At a later step in the operations when the parts referred to have been assembled within a bulb the outer closed end 24 of the exhaust tube 12' is removed usually by cutting it off, and a suitable exhausting pump or other device is applied thereto to bring about the desired evacuation of the tube in a known manner following which'the exhaust tube 12 is sealed off just within the end of the flare to thereby seal off the evacuated bulb.

Not only is it contemplated to produce a perforation substantially within the unction of the three parts as in Figure 3 of the drawing but the perforation 26 may also be formed at the junction of the inner end of the exhaust tube 12 with the side wall of the flare 11 as in Figure 4 of the drawing. This construction avoids the chamber or hollowed-out portion 27 which is shown in Figures 2 and 3 of the drawing.

Instead of closing the outer end of the exhaust tube 12 in advance of the assembling operation referred to, it is contemplated also to place within the end of a normally open tube a closure member 28 such as isshown in Figbein formed of asbestos or the like. g

In the successive operative steps by which the inner end of the flare 11 is softened or rendered plastic, then clamped into welded relation to the adjacent ends of the filament supporting rod and the exhaust tube, and in which the exhaust portis formed, the applicatron of heat is regulated or proportioned in accordance with the requirements of the operative ste 3 that is to be performed. For example, in igure 1 of the drawing a single torch 20 provides an adequate heating effect to soften the lower end of the flare 11 preparatory to the operation of the clamping jaws 21 in the next operative step illustrated in Figure 2.

In the stage of operation disclosed in Figure 2 wherein the parts have been carried bodily from the position wherein the single torch shown in Figure .1 acted on the flare 11, a

plurality of blow torches is made use of to bring about the necessary degree of temperature in the structural parts to be welded as well as in the clamping jaw members 21 to bring about the most effective degree of plasticity to produce a perfect uncture or joining of the interengagcd glass parts.

' In the further step of forming the perforation 26 as in Figures 3, 4 and 5 a pluralityat one end, inside a stem tube with its open end adjacent one end of said stem tube, fusing the vopen end of saidexhaust tube to a portion of said stem tube and thereby sealing said exhaust tube, and heating the air in said exhaust tube while the fused glass is still plastic to cause the air to expand and blow a port through the plastic glass.

2. The method of making a mount for incandescent lamps and other sealed devices which consists in fusing together a supporting rod, a stem tube and the inner end of an exhaust tube closed at its outer end and thereby sealingsaid exhaust tube with plastic glass and thereupon applying heat to the exhaust tube to expand the air in the exhaust tube while the glass is still plastic and causing perforation of the plastic glass to provide a port between the exterior of the stem tube and the interior of the exhaust tube.

3. The method of making stems for incandescent lamps and other sealed devices which consists of positioning an exhaust tube longer than necessary for the finished stem and closed at one end with its open-end inside a 1 stem tube, joining the open end of the exhaust tube to the stem tube by fusion, heating the air in the sealed exhaust tube while the fused juncture is plastic to cause the confined air in the exhaust tube to blow a port through said juncture, and removing the outer sealed end of the exhaust tube.

4. The method of making stems for tubes and bulbs comprising the steps of fusing one end of a glass exhaust tube which is closed at the other end to the wall of a glass stem tube by heating the stem tube sufiiclent- 1y to soften the same at the point of juncture and heating the entrapped air contained in the exhaust tube to blow an-opening through the wall at the softened stem point of juncture therewith.

5. The method of making stems for tubes and bulbs com rising the steps of forming a lateral bend in one end of a glass exhaust tube, closing the other end thereof, and then simultaneously fusing the laterally bent end to the side wall of a glass stem tube and heating the entrapped air contained in the softened stem exhaust tube to blow an opening through the wall at the point of juncture therewith.

6. The method of making stems for tubes and bulbs comprising the steps of simultaneously fusing one end of a glass exhaust tube which is closed at the other end to the wall of a glass stem tube by heating the stem tube sulficiently to soften the same at the point of juncture therewith, heating the entrapped air or gas contained in the exhaust tube to blow an opening through the softened stem wall at the point of juncture therewith and sealing the leading-in wires to one end of the tube.

7. The method according to claim 4 wherein the exhaust tube is fused to the stem tube at a point removed from one endof the latter comprising the step of sealing in to said end loadlng-in wires and a support.

8. The method according to claim 5 wherein the exhaust tube is fused to the stem tube at a point removed from one end of the latter comprising the step of simultaneously sealing in to said end leading-in wires and a suport. p 9. The method of making stems for tubes and bulbs comprising the steps of laterally bending one end of a glass exhaust tube, joining the laterall bent end to the interior of a lass stem tube by relativel rotating the tu es and a burner with the ame from the latter playing upon the exterior of the stem tube and thereby softening a ring of.

FREDERICK RAY. 

